Battery management system, battery pack, electric vehicle, battery management method, and program

Abstract

The present disclosure relates to a battery management system, a battery pack, an electric vehicle, a battery management method, and a program. The battery management system according to the present application includes a battery monitor, a balancer, and a control circuit for controlling the balancer. The control circuit: determines first voltage values representing respective no-load voltages of the batteries; compensates the first voltage values of the batteries by using respective balancing capacities of the batteries based on a balancing process performed during a recent reference time; determines voltage deviations as respective differences between the compensated first voltage values of the batteries and reference voltage values; and can detect an internal short-circuit failure of each of the batteries by comparing a change amount of the respective voltage deviations of the batteries during the reference time with a threshold value.

Description

[0001] This application is a divisional application of the original invention patent application No. 202280006742.8 (International Application No.: PCT / KR2022 / 010982, Application Date: July 26, 2022, Invention Title: Battery Management System, Battery Pack, Electric Vehicle and Battery Management Method). Technical Field

[0002] This disclosure relates to the detection of internal short-circuit faults in batteries.

[0003] This application claims the benefit of Korean Patent Application No. 10-2021-0098141, filed with the Korean Intellectual Property Office on July 26, 2021, the disclosure of which is incorporated herein by reference in its entirety. Background Technology

[0004] Recently, demand for portable electronic products such as laptops, video cameras and mobile phones has grown rapidly, and with the development of electric vehicles, energy storage batteries, robots and satellites, there is a lot of research being done on high-performance batteries that can be recharged.

[0005] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Among them, lithium batteries have little or no memory effect. Therefore, lithium batteries are more popular than nickel-based batteries because they can be recharged at any convenient time, have a very low self-discharge rate, and high energy density.

[0006] To meet the high voltage and high capacity requirements of applications such as electric vehicles, battery systems (e.g., battery packs) that include at least one battery group (i.e., a series connection structure of batteries) are common.

[0007] In a battery system, a fault in a single cell can negatively impact the overall performance and safety of the system. Therefore, accurately detecting faults in individual cells is crucial for battery system management.

[0008] Due to internal / external factors during manufacturing and / or use, there may be characteristic differences between batteries. These characteristic differences lead to voltage imbalance. Balancers are widely used to mitigate voltage imbalance between batteries by performing a balancing (e.g., discharging) operation on each battery.

[0009] Meanwhile, among battery failure types, internal short circuit failure is a major cause of fire, directly or indirectly. An internal short circuit failure occurs when a leakage current path is created due to side reactions and / or impurities entering the battery. Voltage imbalance between batteries has been used to detect batteries with internal short circuit failures.

[0010] However, when performing balancing operations, the voltage imbalance between batteries, which is crucial information for detecting internal short-circuit faults, is mitigated. In other words, the balancing operations performed in the past acted as an obstacle when detecting batteries with internal short-circuit faults. Summary of the Invention

[0011] Technical issues

[0012] This disclosure is designed to solve the above-mentioned problems. Therefore, this disclosure aims to provide a battery management system, battery pack, electric vehicle, and battery management method for accurately detecting batteries with internal short-circuit faults by means of a balancing operation that ensures there is no voltage imbalance between batteries.

[0013] These and other objects and advantages of this disclosure will become apparent from the following description and from the embodiments of this disclosure. Furthermore, it will be readily understood that the objects and advantages of this disclosure can be achieved by the means set forth in the appended claims and combinations thereof.

[0014] Technical solution

[0015] A battery management system according to one aspect of this disclosure includes: a battery monitor configured to detect the voltage of each of a plurality of batteries connected in series; a balancer configured to perform a balancing operation on each battery; and a control circuit configured to control the balancer based on the voltage of each battery detected by the battery monitor. The control circuit is configured to determine a first voltage value indicating a no-load voltage for each battery. The control circuit is configured to compensate for the first voltage value of each battery using the balancing capacity of each battery resulting from the balancing operation within a recent reference time. The control circuit is configured to determine a difference, or voltage deviation, between the compensated first voltage value of each battery and a reference voltage value. The control circuit is configured to detect an internal short-circuit fault in each battery by comparing the amount of change in the voltage deviation of each battery within the reference time with a threshold.

[0016] The control circuit can be configured to increment the fault count of each battery by 1 when the change in voltage deviation of each battery is equal to or greater than a threshold. The control circuit is also configured to detect an internal short-circuit fault in each battery when the fault count of each battery is equal to or greater than a predetermined value.

[0017] The control circuit can be configured to determine a reference voltage value equal to the average or median of the compensated first voltage values ​​of at least two of the plurality of batteries.

[0018] The balancer may include multiple balancing circuits connected in parallel with multiple batteries in a one-to-one correspondence. Each balancing circuit includes a discharge resistor and a discharge switch connected in series.

[0019] The control circuit can be configured to determine the balance capacity of each battery by accumulating the discharge capacity of each battery caused by each balancing operation during a period of reference time.

[0020] The control circuit can be configured to determine the discharge capacity of each cell resulting from each balancing operation by applying a capacity estimation function to first balancing data associated with each balancing operation. The first balancing data includes a second voltage value indicating the no-load voltage of each cell at the start of the balancing operation and the duration of the balancing operation.

[0021] The control circuit can be configured to determine the discharge capacity of each cell resulting from each balancing operation by applying a state-of-charge (SOC) - open-circuit voltage (OCV) mapping to second balancing data for each balancing operation. The second balancing data includes a second voltage value indicating the no-load voltage of each cell at the start of the balancing operation and a third voltage value indicating the no-load voltage of each cell at the end of the balancing operation.

[0022] The control circuit can be configured to determine the estimated SOC of each battery by applying a SOC-OCV mapping to a first voltage value for each battery. The control circuit can be configured to compensate for the estimated SOC of each battery by adding the SOC change corresponding to the balance capacity to the estimated SOC of each battery. The control circuit can be configured to determine a compensated first voltage value by applying a SOC-OCV mapping to the compensated estimated SOC of each battery.

[0023] According to another aspect of this disclosure, the battery pack includes a battery management system.

[0024] According to another aspect of this disclosure, an electric vehicle includes a battery pack.

[0025] A battery management method according to another aspect of this disclosure includes: determining a first voltage value indicating the no-load voltage of each of a plurality of batteries connected in series; compensating the first voltage value of each battery using the balancing capacity of each battery resulting from a balancing operation within a recent reference time; determining the difference or voltage deviation between the compensated first voltage value of each battery and a reference voltage value; and detecting an internal short-circuit fault in each battery by comparing the amount of change in the voltage deviation of each battery within the reference time with a threshold.

[0026] The steps for detecting an internal short-circuit fault in each battery may include: incrementing the fault count of each battery by 1 when the change in voltage deviation of each battery is equal to or greater than a threshold; and detecting an internal short-circuit fault in each battery when the fault count of each battery is equal to or greater than a predetermined value.

[0027] The battery management method may also include determining a reference voltage value as the average or median of the compensated first voltage values ​​of at least two of the plurality of batteries.

[0028] The step of compensating for the first voltage value of each battery may include: determining the estimated SOC of each battery by applying a SOC-OCV mapping to the first voltage value of each battery; compensating the estimated SOC of each battery by adding the SOC change corresponding to the balance capacity to the estimated SOC of each battery; and determining the compensated first voltage value by applying the SOC-OCV mapping to the compensated estimated SOC of each battery.

[0029] Beneficial effects

[0030] According to at least one embodiment of the present disclosure, a battery with an internal short-circuit fault can be accurately detected by means of a balancing operation, in the absence of voltage imbalance between batteries.

[0031] The effects of this disclosure are not limited to those described above, and those skilled in the art will clearly understand these and other effects from the appended claims. Attached Figure Description

[0032] The accompanying drawings illustrate exemplary embodiments of the present disclosure and are used together with the detailed description of the present disclosure below to provide a further understanding of the technical aspects of the present disclosure; therefore, the present disclosure should not be construed as limited to the drawings.

[0033] Figure 1 This is an illustrative diagram showing an electric vehicle according to the present disclosure.

[0034] Figure 2 This is a diagram used for reference when describing an exemplary equivalent circuit of a battery.

[0035] Figures 3 to 6 This is a diagram used for reference when describing the principle of internal short-circuit fault detection in a battery.

[0036] Figure 7 and Figure 8 This is a flowchart illustrating an exemplary battery management method according to a first embodiment of the present disclosure.

[0037] Figure 9This is a flowchart illustrating an exemplary battery management method according to a second embodiment of the present disclosure. Detailed Implementation

[0038] In the following, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms or words used in the specification and appended claims should not be construed as limited to their general or dictionary meanings, but should be interpreted according to their meanings and concepts corresponding to the technical aspects of the present disclosure, based on the principle that the inventor is permitted to appropriately define the terms for the best interpretation.

[0039] Therefore, the embodiments described herein and the illustrations shown in the accompanying drawings are merely exemplary embodiments of this disclosure and are not intended to fully describe the technical aspects of this disclosure. Thus, it should be understood that various other equivalents and modifications may be made thereto at the time of filing of the application.

[0040] Ordinal terms such as “first” and “second” are used to distinguish one element from another among the various elements, but are not intended to limit these elements.

[0041] Unless the context clearly indicates otherwise, it should be understood that, when used in this specification, the term "comprising" specifies the presence of the mentioned elements but does not exclude the presence or addition of one or more other elements. Furthermore, as used herein, the term "control unit" refers to a processing unit that performs at least one function or operation and can be implemented individually or in combination in hardware and software.

[0042] Furthermore, throughout the specification, it should be further understood that when a component is referred to as being “connected to” another component, it may be directly connected to the other component, or there may be an intermediate component.

[0043] Figure 1 This is an illustrative diagram showing an electric vehicle according to the present disclosure.

[0044] Reference Figure 1 The electric vehicle 1 includes a vehicle controller 2, a battery pack 10, and an electrical load 30. The charging / discharging terminals P+ and P- of the battery pack 10 can be electrically connected to a charger 40 via a charging cable. The charger 40 can be included in the electric vehicle 1 or located in a charging station outside the electric vehicle 1.

[0045] The vehicle controller 2 (e.g., an electronic control unit (ECU)) is configured to send a key-on signal to the battery management system 100 in response to a user switching the ignition button (not shown) of the electric vehicle 1 to the ON position. The vehicle controller 2 is also configured to send a key-off signal to the battery management system 100 in response to a user switching the ignition button to the OFF position. The charger 40 can communicate with the vehicle controller 2 and supplies charging power (e.g., constant current, constant voltage, constant power) through the charging / discharging terminals P+ and P- of the battery pack 10.

[0046] The battery pack 10 includes a battery cluster 11, a relay 20, and a battery management system 100.

[0047] Battery set 11 includes batteries B1 to B1. N A series connection structure (N is a natural number of 2 or greater). That is, in battery set 11, batteries B1 to B2 are connected in series. N Series connection. Batteries B1 to B2 N It can include single cells with the same electrical and chemical specifications, or two or more single cells connected in series, in parallel, or both. A single cell is the smallest unit of an energy storage element capable of being charged and discharged independently. For example, single cells are not limited to a specific type and can include any type of cell capable of being repeatedly charged and discharged, such as lithium-ion cells.

[0048] In the following text, in batteries B1 to B N In the public description, the symbol "B" is attached to the battery.

[0049] Relay 20 is connected in series to battery set 11 via a power path that connects battery set 11 and electrical load 30. Figure 1 The relay 20 is shown connected between the positive terminal of the battery pack 11 and a terminal P+ in the charging / discharging terminals. The relay 20 is switched on / off in response to a switching signal from the battery management system 100 and / or the vehicle controller 2. The relay 20 can be a mechanical contactor that switches on / off via the magnetic field of a coil, or a semiconductor switch such as a metal-oxide-semiconductor field-effect transistor (MOSFET).

[0050] The electrical load 30 includes an inverter 31 and an electric motor 32. The inverter 31 is configured to convert direct current (DC) power from the battery pack 11 included in the battery pack 10 into alternating current (AC) power in response to commands from the battery management system 100 or the vehicle controller 2. The electric motor 32 operates using the AC power from the inverter 31. The electric motor 32 may, for example, include a three-phase AC motor.

[0051] When relay 20 is turned on and battery B is charging / discharging, it is called the load condition (cycle condition).

[0052] When relay 20 switches from ON to OFF, battery B is in an unloaded state (idle, calendar), and the battery voltage of battery B in this unloaded state can be referred to as the no-load voltage. No-load voltage is a general term encompassing relaxation voltage and open-circuit voltage (OCV). Specifically, as battery B changes from a loaded state to an unloaded state, its no-load voltage changes as the polarization within battery B decreases. OCV indicates the no-load voltage when the voltage change of battery B is less than a predetermined value if battery B remains in an unloaded state for a predetermined time (e.g., 2 hours) or more. In other words, OCV is the no-load voltage when the polarization of battery B is negligible. Relaxation voltage indicates the no-load voltage with decreasing polarization.

[0053] The battery management system 100 may include a battery monitor 110, a balancer 130, and a control circuit 140. The battery management system 100 may also include a communication circuit 150. In the following description, it is assumed that the battery management system 100 includes the battery monitor 110, the control circuit 140, and the communication circuit 150.

[0054] The battery monitor 110 includes a voltage detection circuit 112. The battery monitor 110 may also include a current detector 114.

[0055] Voltage detection circuit 112 is connected to batteries B1 to B1 included in battery pack 11. N Each of the positive and negative terminals is configured to detect the voltage on battery B (referred to as the battery voltage) and generate a voltage signal indicating the detected battery voltage.

[0056] Current detector 114 is connected in series to battery collection 11 via the current path between battery collection 11 and inverter 31. Current detector 114 may include at least one of known current detection devices, such as a shunt resistor and a Hall effect device. Due to the batteries B1~B N Connected in series, so in batteries B1 to B N A common charging / discharging current flows through it.

[0057] Figure 1 A shunt resistor is shown for the current detector 114. In this case, the voltage detection circuit 112 can output a current signal indicating the direction and amplitude of the charging / discharging current to the control circuit 140 based on the voltage across the shunt resistor. The current detector 114 can directly generate a current signal indicating the charging / discharging current flowing through the battery pack 11 and output it to the control circuit 140.

[0058] The balancer 130 is configured to balance batteries B1 to B in response to a balancing command from the control circuit 140. N The balancing operation is performed on battery B, which needs to be balanced. In the following text, battery B, identified as needing balancing, is referred to as the "target battery". Balancing commands can be directed to batteries B1 through B2. N The target time for target battery B. Target time refers to the required equilibration duration for target battery B.

[0059] Figure 1 It shows the balancing circuits D1~D N Example of a balancer 130. Balancing circuits D1~D N They can be connected in parallel to batteries B1~B in a one-to-one correspondence. N In the following text, in the balanced circuit D1~D N In the public description, the symbol "D" is attached to the battery.

[0060] The balancing circuit D is a series circuit of discharge resistor 131 and discharge switch 132. Discharge switch 132 is turned on in response to a balancing command. When discharge switch 132 is turned on, battery B discharges through discharge resistor 131. Discharge switch 132 can be a semiconductor switch such as a MOSFET.

[0061] The control circuit 140 can be operatively connected to the relay 20, the battery monitor 110, the balancer 130, and the communication circuit 150. Operable connection means direct / indirect connection to send and receive signals in one or both directions.

[0062] The control circuit 140 may be referred to as a "battery controller" and may be implemented in hardware using at least one of a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field-programmable gate array (FPGA), a microprocessor, or an electronic unit for performing other functions.

[0063] Control circuitry 140 can collect voltage and / or current signals from battery monitor 110. In one example, control circuitry 140 can use an analog-to-digital converter (ADC) configured therein to convert and record the analog signals collected from battery monitor 110 as digital values. Alternatively, battery monitor 110 itself can send the results of converting analog signals to digital values ​​to control circuitry 140.

[0064] Memory 141 may include, for example, at least one type of storage medium selected from flash memory, hard disk, solid-state drive (SSD), silicon disk drive (SDD), multimedia card micro, random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), or programmable read-only memory (PROM). Memory 141 may store data and programs required for the computational operations of control circuit 140. Memory 141 may store data indicating the results of the computational operations of control circuit 140. Memory 141 may store given functions, logic, and algorithms for use in detecting internal short-circuit faults in battery B. Memory 141 may be integrated into control circuit 140.

[0065] Control circuit 140 can activate relay 20 in response to a key-on signal from vehicle controller 2. Control circuit 140 can deactivate relay 20 in response to a key-off signal from vehicle controller 2. The key-on signal is a signal requesting a switch from a no-load state to a loaded state. The key-off signal is a signal requesting a switch from a loaded state to a no-load state. Alternatively, instead of control circuit 140, vehicle controller 2 can be responsible for controlling the activation / deactivation of relay 20.

[0066] The control circuit 140 is configured to control the balancer 130 based on the voltage of battery B detected by the battery monitor 110.

[0067] Control circuit 140 can monitor each battery B1~B N Identify battery B1~B using voltage N The maximum and minimum voltages. The maximum voltage is for batteries B1~B1. N The highest voltage among the voltages. The lowest voltage is for batteries B1~B2. N The lowest voltage among the voltages.

[0068] Communication circuit 150 is configured to support wired or wireless communication between control circuit 140 and vehicle controller 2. Wired communication may be, for example, Controller Area Network (CAN) communication, and wireless communication may be, for example, Zigbee or Bluetooth communication. The communication protocol is not limited to a specific type and may include any type of communication protocol that supports wired / wireless communication between control circuit 140 and vehicle controller 2. Communication circuit 150 may include output devices (e.g., a display, a speaker) to provide information received from control circuit 140 and / or vehicle controller 2 in a user-readable format.

[0069] The operation performed by control circuit 140 to detect internal short-circuit faults in the battery will be described in detail below.

[0070] Control circuit 140 determines the no-load voltage value of battery B.

[0071] When battery B is in an unloaded state, control circuit 140 can determine the no-load voltage value of battery B as equal to the voltage value of battery B detected by battery monitor 110.

[0072] When battery B is under load, control circuit 140 can use a battery state estimation algorithm to determine (estimate) the no-load voltage of battery B based on the battery voltage detected by battery monitor 110 and the charging / discharging current of battery B detected by current detector 114. In one example, according to Ohm's law, the no-load voltage of battery B can be estimated by subtracting the voltage corresponding to the product of the charging / discharging current of battery B and the internal resistance of battery B from the battery voltage detected by battery monitor 110.

[0073] Alternatively, regardless of whether battery B is in an unloaded or loaded state, control circuit 140 can use a predetermined battery state estimation algorithm to determine the estimated state of charge (SOC) of battery B, and map it from a given SOC-OCV (see reference). Figure 5 The OCV value associated with the estimated SOC of battery B is obtained. Battery state estimation algorithms can include known algorithms (e.g., Kalman filters).

[0074] Control circuit 140 determines the battery B1~B N The target battery B is located in the battery set 11. When the battery set 11 changes from a loaded state to an unloaded state, the control circuit 140 can determine whether batteries B1 to B2 need to be adjusted. N At least one of them performs a balancing operation. The determination of the presence or absence of target battery B can be performed periodically in the no-load condition, starting from the time when battery set 11 changes from a loaded condition to a no-load condition (i.e., from the beginning of the no-load condition).

[0075] In one example, control circuit 140 can adjust the no-load voltage ratio of batteries B1 to B2. N The minimum no-load voltage of battery B is set as the target battery if it is higher than the reference value or more. In another example, the control circuit 140 can estimate the SOC of batteries B1 to B2. N The minimum SOC of the battery B is set to be higher than the reference value or more.

[0076] Control circuit 140 can determine the target capacity of target battery B to be equal to that of target battery (e.g., B). i ) and reference battery (e.g., B) jThe capacity corresponding to the voltage difference (or SOC difference) between batteries B1 and B2. The reference battery refers to batteries B1 to B2. N The target time corresponds to the minimum no-load voltage (or minimum SOC) of the battery. Control circuit 140 can determine the target time for target battery B using a given mapping as the correlation between target capacity and target time. The correlation between target capacity and target time can be determined by experiments performed on batteries having the same electrical and chemical properties as battery B.

[0077] Alternatively, upon receiving a balancing command, the balancer 130 can perform a balancing operation on the target battery B within a first time period and stop the balancing operation within a second time period. Whenever the balancing operation of the balancer 130 stops, the control circuit 140 can re-balance batteries B1 to B2. N The system identifies the target battery B and sends a balancing command for the target battery B to the balancer 130.

[0078] The balancing command can be a high-level voltage applied directly to the discharge switch 132 to switch it from open to closed. When no balancing command is received, the discharge switch 132 can remain open.

[0079] Simultaneously, when a switch from no-load to loaded condition is requested during the balancing operation of target battery B, control circuit 140 can output a balancing stop command to balancer 130. Balancer 130 can then terminate the balancing of all batteries B1 to B2 in response to the balancing stop command. N The balancing operation.

[0080] Figure 2 This diagram is used for reference when describing an exemplary equivalent circuit of a battery. In this specification, a normal battery refers to batteries B1 to B2. N There are no batteries with internal short circuit faults, and the faulty batteries refer to batteries B1 to B2. N The battery is experiencing an internal short circuit fault.

[0081] Reference Figure 2 A normal battery can be equivalent to a DC voltage source V. DC The internal resistor R0 and the RC circuit connected in series with R1 and C. Conversely, a faulty battery can be equivalent to an additional resistor R. ISC A series circuit connected between the two terminals of a series circuit corresponding to a normal battery. Additional resistor R. ISC Used as leakage current I ISC The path. For reference, DC voltage source V DC The voltage is OCV of battery B, and the battery voltage is DC voltage source V. DCThe total voltage of the internal resistor R0 and the series circuit of RC with R1 and C. When the voltage across RC with R1 and C is zero (0V), the relaxation voltage is equal to OCV.

[0082] During the charging of the faulty battery, some charging power is not stored in the faulty battery and is instead released as leakage current I. ISC It is consumed. Furthermore, during the discharge of the faulty battery, some discharge power is not supplied to the electrical load 30 and is instead used as leakage current I. ISC Consumed. Resistor R ISC The decrease in resistance indicates that the internal short-circuit fault has worsened, and as the internal short-circuit fault worsens, the leakage current I increases. ISC The power consumption may increase.

[0083] As a result, during charging, the voltage change of the faulty battery (i.e., the increase in SOC) is smaller than that of the normal battery. Conversely, during discharging, the voltage change of the faulty battery (i.e., the decrease in SOC) is greater than that of the normal battery. Furthermore, even under no-load conditions, the energy stored in the faulty battery also acts as a leakage current I. ISC Consumed.

[0084] Figures 3 to 6 This is a diagram used for reference when describing the principle of internal short-circuit fault detection in a battery.

[0085] Figure 3 Battery B is shown in sequence. i and battery B j The time-dependent variation of the no-load voltage of each of the components in the battery set 11 during the periods of being under load (charging), under no load, under load (discharging), and under no load. Figure 3 In the middle, assume battery B i It is a normal battery, and battery B j It's a faulty battery.

[0086] Reference Figure 3 Curve 310 shows battery B i The no-load voltage, and curve 320 shows the battery B. j The no-load voltage. Time tB is the detection timing, that is, the control circuit 140 detects battery B1~B N The time of the faulty battery. Time tA is earlier than time tB by the reference time Δt. REF The past time. A reference time Δt can be preset. REF The length of . To help understand, assume battery B. i No-load voltage and battery B j The no-load voltage is equal at time tA.

[0087] The time period from time tA to time t1 is the charging period, and battery B i and battery B j The no-load voltage continues to rise. However, battery B... j No-load voltage ratio of battery B i It rises more slowly, and battery B i and battery B j The voltage difference between batteries gradually increases during the charging period tA to t1. In other words, for the charging period tA to t1, the voltage difference between batteries B1 and B2 gradually increases. N The voltage imbalance between them gradually worsened.

[0088] The time period from time t1 to time t4 is a no-load period, and battery B i and battery B j Charging / discharging stops. Due to leakage current (see...) Figure 2 Battery B j The no-load voltage decreases slowly during the no-load period t1~t4. Meanwhile, the period from time t2 to time t3 is when the operation targeting battery B is performed. i The balancing operation period, i.e., battery B i The balancing period. Control circuit 140 switches batteries B1 to B2 between time t1 and time t2. N Battery B in i Set as the target battery. In one example, when battery B... j The no-load voltage of battery B1 to B1 in time t1 is... N At the minimum no-load voltage, battery B i The no-load voltage is higher than that of battery B. j The no-load voltage, therefore battery B i Set as the target battery. Among the remaining batteries, at least one battery with a no-load voltage lower than the minimum no-load voltage can be additionally set as the target battery. When performing an operation targeting battery B... i During the balancing operation, battery B i The no-load voltage of batteries B1 to B2 continuously decreases during the equilibrium period t2~t3. In other words, for the equilibrium period t2~t3, the voltage of batteries B1~B2 decreases continuously. N The voltage imbalance between them gradually lessens.

[0089] The time period from time t4 to time t5 is the discharge period, and battery B... i and battery B j The no-load voltage of battery B continues to decrease. j The no-load voltage drop is greater than that of battery B. i Faster, and battery B i and battery B jThe voltage difference between batteries gradually increases again during the discharge period t4 to t5. In other words, for the discharge period t4 to t5, the voltage difference between batteries B1 and B2 gradually increases again. N The voltage imbalance gradually worsened.

[0090] The time period from time t5 to time tB is a no-load period. Battery B j The no-load voltage decreases slowly during the no-load period t5~tB. The time period from time t6 to time t7 is the battery B. i The balancing period. Control circuit 140 sets the battery B1~B1 balance between time t5 and time t6. N The target battery. In one example, battery B is placed at time t6 in the same manner as at time t2. i Set as the target battery. When executing for battery B i During the balancing operation, battery B i The no-load voltage of battery B1 continuously decreases during the equilibrium period t6 to t7. In other words, for the equilibrium period t6 to t7, the voltage of battery B1 to B2 decreases continuously. N The voltage imbalance between them was reduced again.

[0091] According to reference Figure 3 The above description refers to each execution targeting battery B. i During the balancing operation, battery B i and battery B j The no-load voltage difference between them decreases. Therefore, it is impossible to change the voltage difference between batteries B1 and B2 at time tB (internal short-circuit fault detection timing). N Battery B is identified by comparing its no-load voltage with a certain threshold. j Is it malfunctioning?

[0092] This disclosure uses the most recent reference time Δt based on the internal short-circuit fault detection timing (time tB). REF Each battery B1 to B during the time period (i.e., tA to tB) N Balanced capacity compensation for each cell B1 to B at the detection timing (time tB) N The no-load voltage value. The compensated voltage value of battery B indicates the estimated no-load voltage of battery B at the detection timing (time tB) when no balancing operation is performed for battery B during the time period tA to tB. Therefore, even at the detection timing (time tB), batteries B1 to B N The voltage imbalance between them is not significant, so battery B can also be used. j The test result indicates a fault.

[0093] The control circuit 140 can detect multiple batteries B1 to B at each detection timing within a predetermined time interval. N The faulty battery in the example. In one example, the reference time Δt...REF It can be 100 times larger than the time interval between two adjacent detections, and a moving window can be used to define the nearest reference time Δt. REF The time period. When the detection condition is met, the control circuit 140 can detect an internal short-circuit fault. The detection condition can be, for example, for all of the multiple batteries B1 to B2. N The balance of all loads has stopped in a no-load condition.

[0094] The balancing capacity of battery B during the time period tA to tB is the cumulative value of the discharge capacity of battery B resulting from balancing operations during the time period tA to tB, i.e., the total discharge capacity during the time period tA to tB. Batteries that have never undergone balancing operations during the time period tA to tB (e.g., B) will be excluded. j The balance capacity is determined to be 0Ah.

[0095] The principle for determining the discharge capacity each time a balancing operation is performed will be described below.

[0096] Figure 4 It shows Figure 3 During the no-load period t1~t4, the target battery B i The balancing operation. Curves 410 and 411 respectively show the balancing operation of battery B. i The time-dependent changes in no-load voltage and discharge capacity of battery B. i The no-load voltage value of battery B remains at V2 from time t1 to time t2, decreases continuously from time t2 to time t3, and reaches V3 at time t3. Time t3 is the time when battery B... i The equilibrium end time.

[0097] Control circuit 140 can determine the battery B caused by the balancing operation by applying a capacity estimation function to the first balancing data of the balancing operation. i The discharge capacity of battery B. The first balancing data includes the initial voltage value and the duration of the balancing operation. The initial voltage value indicates the battery B's discharge capacity at the start time t2 of the balancing operation. i The no-load voltage, and Figure 4 In the table, the initial voltage value is V2. The duration indicates the length of time from the equilibrium start time t2 to the equilibrium end time t3, and... Figure 4 In the middle, the duration is Δt BC = t3-t2.

[0098] The capacity estimation function defines the correlation between the initial voltage value, duration, and discharge capacity, and can be determined through experiments performed on a battery with the same electrical and chemical properties as battery B. Equation 1 below is an example of a capacity estimation function.

[0099] Equation 1

[0100] In equation 1 above, V start This is the initial voltage value, Δt. BC This refers to the duration, R is the preset resistance of the discharge resistor 131, and Q... dis This is the discharge capacity at each equilibrium step. V start / R indicates the balancing current flowing through discharge resistor 131 at the start of balancing operation.

[0101] Equation 2 below is another example of a capacity estimation function.

[0102] Equation 2

[0103] In equation 2 above, V end It is the final voltage value, and the other factors are the same as in Equation 1.

[0104] Alternatively, control circuit 140 can determine the battery B caused by the balancing operation by applying the SOC-OCV mapping to second balancing data during the balancing operation. i The discharge capacity. The second balancing data includes the start and end voltage values ​​of the balancing operation. The end voltage value indicates the no-load voltage at the end of the balancing operation, and... Figure 4 In the middle, the end voltage value is V3. Figure 5 An example of SOC-OCV mapping is shown. (See reference...) Figure 5 Z2 is the state of charge (SOC) corresponding to the initial voltage value V2, and Z3 is the SOC corresponding to the final voltage value V3. The control circuit 140 can multiply the difference between the two SOCs (i.e., Z2 - Z3) by the battery B. i The full charge capacity (FCC) is used to determine the battery B caused by the balancing operation during the balancing period t2~t3. i The discharge capacity. Methods for estimating the full capacity are well-known, and their detailed description is omitted.

[0105] Alternatively, the balance capacity of battery B can be directly calculated by integrating the balance current calculated periodically by applying Ohm's law to the voltage and resistance of discharge resistor 131 from the start to the end of the balance operation.

[0106] The balancing capacity can be determined each time a balancing operation is performed.

[0107] Battery B is executed twice within the time period tA to tB. iThe balancing operation. Therefore, the control circuit 140 can determine the battery B in the time period tA to tB by summing the discharge capacity during the balancing period t2~t3 and the discharge capacity during the balancing period t6~t7. i Balanced capacity or from battery B i Total capacity consumed.

[0108] Reference Figure 5 The control circuit 140 can determine the timing of each battery B1 to B1 at the detection time (time tB). N The estimated SOC. In one example, when battery B is detected at time tB. i The voltage value of the no-load voltage is V i At that time, the control circuit 140 can apply the SOC-OCV mapping to the voltage value V. i To be related to voltage value V i Corresponding Z i It was identified as battery B. i The estimated SOC.

[0109] Control circuit 140 can apply the predetermined voltage compensation logic as described below to the most recent reference time Δt based on the detection timing (time tB). REF Each battery B1 to B inside N The balanced capacity is used to compensate for the deficiencies of each battery B1 to B2. N The voltage value of the no-load voltage. Specifically, the control circuit 140 can control the battery B... i Balance capacity divided by battery B i The full charge capacity determines the battery B i SOC change ΔZ i The control circuit 140 measures the change in SOC ΔZ. i Compared with the estimated SOC Z i Add up to battery B i The estimated SOC from Z i Compensation to Z i+ The control circuit 140 applies the SOC-OCV mapping to the compensated estimated SOC Z. i+ Determine the corresponding Z i+ voltage value V i+ Voltage value V i+ It uses battery B i Balanced capacity to compensate for voltage value V i The result. Conversely, since battery B was never tested during the time period tA~tB. j A balancing operation is performed, so battery B... j The compensated voltage value V j+ Equal to the voltage value V detected at time tB j .

[0110] Return to reference Figure 3 Curve 311 is achieved by passing battery B i The time-related changes in the equilibrium capacity are applied to curve 310 to compensate for the results of curve 310. That is, curve 311 shows that when no action is taken for battery B during the time period tA~tB... i During the balancing operation of battery B i The time-dependent variation of the no-load voltage. Since no balancing operation is performed during the charging period tA–t1, curves 310 and 320 completely overlap during this period. Furthermore, since no balancing operation is performed during the discharging period t4–t5, the difference between curves 310 and 320 remains constant during this period. Figure 5 As shown, due to the detection timing tB, battery B i The voltage value from V i Compensation to V i+ Therefore, it can be seen that it is related to battery B. j voltage value V j The differences have widened.

[0111] The above series of processes (voltage compensation logic) are commonly applied to all batteries B1 to B at each detection timing. N The control circuit 140 can determine the reference voltage value equal to that of batteries B1 to B at each detection timing. N The reference voltage value is the average or median of two or more compensated voltage values. In other words, the reference voltage value can be updated at each detection interval. In one example, the reference voltage value could be for batteries B1 to B2. N The determined values ​​are (i) the average or median of all compensated voltage values ​​or (ii) the average or median of a predetermined number of compensated voltage values ​​arranged in descending order. (Refer to...) Figure 3 V R This is the reference voltage value at time tB. Alternatively, the reference voltage value can be a given value, but related to the voltage values ​​of batteries B1 to B2. N It is unrelated to voltage changes.

[0112] Control circuit 140 can determine the voltage deviation or difference between the compensated voltage value of battery B and the reference voltage value at each detection timing. Furthermore, control circuit 140 can record a time series in memory 141, indicating the most recent reference time Δt. REFWithin the time period tA to tB, the time-related changes in the voltage deviation of battery B are determined sequentially multiple times. When some detection timing voltage deviations of battery B within the time period tA to tB are omitted, the omitted voltage deviation values ​​can be added to the time series by applying interpolation to the remaining voltage deviation values ​​within the time series. Figure 6 In the diagram, curves 610 and 620 respectively show battery B. i Voltage deviation and battery B j The time-dependent variation of voltage deviation.

[0113] Control circuit 140 can determine the most recent reference time Δt. REF The change in voltage deviation of battery B during the period. Figure 6 In the middle, ΔV iA and ΔV iB These are batteries B. i The voltage deviation at times tA and tB, and battery B i The change in voltage deviation is ΔV iA -ΔV iB Furthermore, ΔV jA and ΔV jB These are batteries B. j The voltage deviation at times tA and tB, and battery B j The change in voltage deviation is ΔV jA -ΔV jB For reference, see below. Figure 3 ΔV iB =V i+ -V R And ΔV jB =V j+ -V R .

[0114] Control circuit 140 determines whether battery B is in an internal short-circuit fault by comparing the change in voltage deviation of battery B with a threshold at each detection timing. In one example, at time tB (ΔV iA -ΔV iB ) < threshold ≤ (ΔV) jA -ΔV jB In the case of battery B, i It was determined to be normal, and battery B was removed. j It has been identified as a fault.

[0115] The control circuit 140 can count the number of times the change in voltage deviation of battery B is continuously equal to or greater than a threshold by comparing the change in voltage deviation of battery B with a threshold at each detection timing, and determine that battery B is in an internal short circuit fault when the counted number reaches a predetermined number.

[0116] Figure 7 and Figure 8 This is an exemplary flowchart illustrating a battery management method according to a first embodiment of the present disclosure. Figure 7 The method can be repeated at predetermined time intervals. To aid understanding, it will be assumed that the execution occurs at time tB. Figure 7 The following description applies to methods that are described in this context.

[0117] Reference Figures 1 to 7 In step S700, the control circuit 140 determines a first voltage value indicating the no-load voltage of battery B. For example, Figure 3 V i and V j Indicate battery B respectively i The first voltage value and the first voltage value of battery Bj.

[0118] In step S710, the control circuit 140 uses the balance capacity of battery B to compensate for the first voltage value of battery B. Step S710 may include... Figure 8 The subroutines S810, S820, S830, and S840 are shown in the diagram.

[0119] In step S810, the control circuit 140 determines the estimated SOC of battery B by applying the SOC-OCV mapping to a first voltage value of battery B. (Refer to...) Figure 5 Z i It is with battery B i The first voltage value V i Corresponding battery B i The estimated SOC.

[0120] In step S820, control circuit 140 determines the balance capacity of battery B. The balance capacity of battery B can be determined at the most recent reference time Δt. REF The cumulative value of the discharge capacity resulting from the balancing operation performed on battery B.

[0121] In step S830, the control circuit 140 compensates for the estimated SOC of battery B by adding the SOC change corresponding to the balance capacity to the estimated SOC of battery B. (Refer to...) Figure 5 By ΔZ i With Z i Add them together to get battery B i The compensated estimated SOC Z i+ .

[0122] In step S840, control circuit 140 determines a compensated first voltage value for battery B by applying a SOC-OCV mapping to the compensated estimated SOC of battery B. (Refer to...) Figure 5The compensated first voltage value of battery B is determined to be equal to that of Z. i+ Corresponding V i+ .

[0123] In step S720, the control circuit 140 determines the reference voltage value. Figure 3 V in R It is the reference voltage value at time tB.

[0124] In step S730, the control circuit 140 determines the voltage deviation of battery B as equal to the difference between the compensated first voltage value of battery B and the reference voltage value. (Refer to...) Figure 6 ΔV iB and ΔV jB These are batteries B. i Voltage deviation and battery B j Voltage deviation.

[0125] In step S740, the control circuit 140 determines the most recent reference time Δt. REF The change in voltage deviation of battery B within the battery. (Refer to...) Figure 6 , (ΔV iA -ΔV iB ) is battery B i The change in voltage deviation, and (ΔV) jA -ΔV jB ) is battery B j The change in voltage deviation.

[0126] In step S750, the control circuit 140 determines whether the change in voltage deviation of battery B is equal to or greater than a threshold. When the value of step S750 is "yes", step S760 is executed.

[0127] In step S760, control circuit 140 detects an internal short-circuit fault in battery B. Furthermore, control circuit 140 can perform a predetermined protection operation. The protection operation may include outputting a diagnostic message notifying battery B of an internal short-circuit fault. The diagnostic message can be transmitted to vehicle controller 2 via communication circuit 150. Communication circuit 150 may output a warning signal to the user upon receiving the diagnostic message.

[0128] Figure 9 This is a flowchart illustrating an exemplary battery management method according to a second embodiment of the present disclosure. Figure 9 The method can be repeated at predetermined time intervals. To aid understanding, it will be assumed that the execution occurs at time tB. Figure 9 The following description applies to methods that are described in this context.

[0129] Reference Figure 9The process from step S700 to step S740 is the same as in the first embodiment. After executing step S740, step S910 is executed. In step S910, the control circuit 140 determines whether the change in voltage deviation of battery B is equal to or greater than a threshold. When the value of step S910 is "yes", step S920 is executed. When the value of step S910 is "no", step S922 is executed.

[0130] In step S920, control circuit 140 increments the fault count of battery B by 1. In step S922, control circuit 140 resets the fault count of battery B to an initial value (e.g., 0).

[0131] In step S930, the control circuit 140 determines whether the fault count of battery B is equal to or greater than a predetermined value. That is, the control circuit 140 determines whether the number of times the voltage deviation change of battery B is equal to or greater than a threshold has been continuously counted a predetermined number of times. When the value of step S930 is "yes", step S940 is executed.

[0132] In step S940, the control circuit 140 detects an internal short-circuit fault in battery B. In the same manner as in the first embodiment, the control circuit 140 can perform a predetermined protection operation.

[0133] The second embodiment, a variation of the first embodiment, can prevent erroneous fault detection.

[0134] The embodiments of the present disclosure described above can be implemented not only by apparatus and method, but also by a program that performs functions corresponding to the configuration of the embodiments of the present disclosure or a recording medium on which the program is recorded. Those skilled in the art can easily implement such implementations from the disclosure of the above embodiments.

[0135] While this disclosure has been described above with respect to a limited number of embodiments and accompanying drawings, this disclosure is not limited thereto, and it will be apparent to those skilled in the art that various modifications and alterations can be made to it within the technical aspects of this disclosure and within the equivalent scope of the appended claims.

[0136] Furthermore, without departing from the technical aspects of this disclosure, those skilled in the art can make many substitutions, modifications and alterations to the disclosure described above. This disclosure is not limited to the above embodiments and drawings, and all or some embodiments can be selectively combined to allow various variations.

[0137] (Description of reference numerals in the attached figures)

[0138] 1: Electric vehicles

[0139] 10: Battery Pack B: Battery

[0140] 100: Battery Management System

[0141] 110: Battery Monitor 130: Balancer

[0142] 140: Control circuit.

Claims

1. A battery management system, the battery management system comprising: At least one processor; as well as The memory stores programs that can be executed by the at least one processor. Wherein, when the program is executed by the at least one processor, the at least one processor: Obtain the no-load voltage value of each of the multiple batteries. With the balancing operation for the plurality of batteries stopped, the no-load voltage value of each battery is compensated using the balancing capacity of each battery obtained from the previously performed balancing operation. Determine the voltage difference between the compensated no-load voltage value and a reference voltage value of at least one of the plurality of batteries, and The fault in the at least one battery is detected based on the change in the voltage difference of the at least one battery.

2. The battery management system according to claim 1, wherein, When the program is executed by the at least one processor, the at least one processor causes the at least one processor to: When the change in the voltage difference of the at least one battery is equal to or greater than a threshold, the fault count of the at least one battery is incremented by 1, and A fault is detected in the at least one battery when the fault count of the at least one battery is equal to or greater than a predetermined value.

3. The battery management system according to claim 1, wherein, The reference voltage value is the average or median of the compensated no-load voltage values ​​of at least two of the plurality of batteries.

4. The battery management system according to claim 1, wherein, When the program is executed by the at least one processor, the at least one processor causes the at least one processor to compensate for the no-load voltage value of each battery using the balanced capacity of each battery obtained from the previously executed balancing operation performed within a reference time. The reference time is longer than the duration of the balancing operation.

5. The battery management system according to claim 1, wherein, When the program is executed by the at least one processor, the at least one processor determines the balance capacity of each battery by accumulating the discharge capacity of each battery obtained through each balance operation over a period of reference time.

6. The battery management system according to claim 5, wherein, When the program is executed by the at least one processor, the at least one processor determines the discharge capacity of each battery obtained through each balancing operation by applying a capacity estimation function to first balancing data associated with each balancing operation, and The first balancing data includes the no-load voltage value of each battery at the start of the balancing operation and the duration of the balancing operation.

7. The battery management system according to claim 5, wherein, When executed by the at least one processor, the program causes the at least one processor to determine the discharge capacity of each battery obtained through each balancing operation by applying a state-of-charge (SOC) to open-circuit voltage (OCV) mapping to second balancing data for each balancing operation, and The second balancing data includes the no-load voltage value of each battery at the start of the balancing operation and the no-load voltage value of each battery at the end of the balancing operation.

8. The battery management system according to claim 1, wherein, When the program is executed by the at least one processor, the at least one processor causes the at least one processor to: The estimated SOC of each cell is determined by applying the SOC-OCV mapping to the no-load voltage value for each cell. The estimated SOC of each battery is compensated by adding the SOC change corresponding to the balanced capacity to the estimated SOC of each battery. The compensated no-load voltage value is determined by applying the SOC-OCV mapping to the compensated estimated SOC of each battery.

9. A battery pack comprising a battery management system according to any one of claims 1 to 8.

10. An electric vehicle comprising a battery pack according to claim 9.

11. A battery management method, the battery management method comprising the following steps: Obtain the no-load voltage value of each of the multiple batteries; When the balancing operation for the plurality of batteries is stopped, the no-load voltage value of each battery is compensated using the balancing capacity of each battery obtained from the balancing operation performed in the past. Determine the voltage difference between the compensated no-load voltage value and the reference voltage value of at least one of the plurality of batteries; as well as The fault in the at least one battery is detected based on the change in the voltage difference of the at least one battery.

12. The battery management method according to claim 11, wherein, The steps for detecting a fault in at least one battery include the following: When the change in the voltage difference of the at least one battery is equal to or greater than a threshold, the fault count of the at least one battery is incremented by 1; and A fault is detected in the at least one battery when the fault count of the at least one battery is equal to or greater than a predetermined value.

13. The battery management method according to claim 11, wherein, The reference voltage value is the average or median of the compensated no-load voltage values ​​of at least two of the plurality of batteries.

14. The battery management method according to claim 11, wherein, The step of compensating for the no-load voltage value of each battery includes the following steps: The estimated SOC of each cell is determined by applying the state of charge (SOC)-open circuit voltage (OCV) mapping to the no-load voltage value of each cell; The estimated SOC of each battery is compensated by adding the SOC change corresponding to the balanced capacity to the estimated SOC of each battery; and The compensated no-load voltage value is determined by applying the SOC-OCV mapping to the compensated estimated SOC of each cell.

15. A program, when executed by at least one processor, for performing the battery management method according to any one of claims 11 to 14.

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